Welcome to our forum.
Nordic makes a quality, entry level hot tub however Hot Springs and Arctic are considered to be two the to premier brands in the industry. I am a Nordic dealer and while I feel they make a quality, basic hot tub, they really do not belong in the conversation with the other two you have looked at, hence the drastic price difference. Hot Spring's offers ACE and Arctic offers Onzen which are basically salt water chlorine generators whereas Nordic does not. Nothing is chemical free.I would recommend having you and your wife wet test each of the three models you are looking at. Then compare the dealers and your trust and comfort in each. Then you can better decide on which hot tub is right for you.